Enclosed piping and exhaust systems that convey fluids at pressure are subject to standing wave resonances or resonant pulsations which can damage or destroy the various components of the piping system if allowed to continue unchecked. The standing wave resonances are typically comprised of pulsation waves or pulses traveling back and forth through a section of the piping system at a velocity or “speed of sound” which can be many times greater than the speed of the flowing fluid. The speed of sound through a fluid medium is proportional to the stiffness of the fluid divided by its density, and in a gas is highly dependent upon temperature. If an effective length of the piping system matches an integer or harmonic multiple of the wavelength of a particular acoustical frequency, and if a source of pressure pulsations provides a pressure pulse at that particular frequency, a self-reinforcing standing wave resonance can develop which can destroy or seriously damage the piping system and associated equipment. If the fluid is an incompressible liquid such as water, the resonant pulsations can create an effect similar to “hydraulic hammer”. If the fluid is a gas, the pulsations can be known as an “acoustic” or “standing-wave” resonance or high-energy infinite wave.
Great efforts are often expended to eliminate hydraulic hammer and acoustic resonances from enclosed and pressurized piping and exhaust systems. These efforts can include tuning the piping system away from any harmonic alignment with a pulsation source, such as an engine, compressor, pump, flow valve or other source of disturbance, etc., or adding pulsation dampeners, silencers, accumulators or similar pulsation suppression device to the piping system. If conditions change, however, such as temperature of the gas or the excitation frequency from the pulsation source, a standing wave resonance may still begin to build up in one or more segments of the piping system.